Systems and methods for measuring the rate of angular displacement using magnetic field sensing

Abstract

This invention discloses a method for measuring the rate of angular displacement, of a traveling object, using magnetic field sensing, said method comprising: measuring magnetic field intensity and/or changes in said magnetic field intensity, projected onto a magnetic field sensor coupled to said traveling object, each measurement being per orthogonal rotation axis to provide a magnetic field intensity value per axis and/or a change in magnetic field intensity per axis, as said object's orientation changes with time; determining, number of peaks, present in a measurement sample comprising a set of said measurements, of time duration; and computing said rate of angular displacement, for said traveling object, as a function of said determined number of peaks and said time duration.

The invention claimed is: 
     
       1. A method for measuring the rate of angular displacement of a traveling object about one or more axes orthogonal to one another using magnetic field sensing, the method comprising: measuring magnetic field intensity and/or changes in the magnetic field intensity, projected onto a magnetic field sensor coupled to the traveling object, to generate scalar measurements over a time duration of the magnetic field intensity and/or changes in the magnetic field intensity, wherein each of the scalar measurements corresponds to one of the orthogonal axes; providing noise-immunity in the measurements with a comparator; determining, with a processor, a number of peaks in the measurements for the time duration, wherein the number of peaks is determined from determining regions where the measurements have a zero slope for the time duration; and computing the rate of angular displacement for the traveling object, as a function of the determined number of peaks and the time duration. 
     
     
       2. The method as claimed in  claim 1 , wherein the method further comprises:
 determining a value proportional to a frequency of the determined number of peaks, detected by a peak counter, in the measurements. 
 
     
     
       3. The method as claimed in  claim 1 , wherein the computing further determines,
 angular displacement of the traveling object for each of the orthogonal axes; 
 rate of angular displacement of the traveling object for each of the orthogonal axes; and/or 
 change in angle and/or orientation of the object. 
 
     
     
       4. The method as claimed in  claim 1 , wherein the magnetic field sensor is a single device with three orthogonal sense axes. 
     
     
       5. The method as claimed in  claim 1 , wherein the magnetic field sensor is a sensor selected from a group consisting of, a 1-axis magnetic field sensor, a 2-axis magnetic field sensor, and a 3-axis magnetic field sensor. 
     
     
       6. The method as claimed in  claim 1 , further comprising:
 varying the number of measurements and/or varying the time duration based on a magnetic field across a trajectory of the object. 
 
     
     
       7. A system for measuring the rate of angular displacement of a traveling object about one or more axes orthogonal to one another using magnetic field sensing, the system comprising: a magnetic field sensor configured to measure magnetic field intensity and/or changes in the magnetic field intensity, projected onto the magnetic field sensor, to generate scalar measurements over a time duration of the magnetic field intensity and/or changes in the magnetic field intensity, wherein each of the scalar measurements corresponds to one of the orthogonal axes; a comparator configured to provide noise-immunity in the measurements; at least one processor coupled with a non-transitory computer readable storage medium storing instructions that, when executed by the processor, cause the processor to: determine a number of peaks in the measurements for the time duration, wherein the number of peaks is determined from determining regions where the measurements have a zero slope for the time duration and compute the rate of angular displacement for the traveling object, as a function of the determined number of peaks and the time duration. 
     
     
       8. The system as claimed in  claim 7 , wherein the processor, with instructions, is further configured to: determine changing magnetic field intensity of the magnetic field about each of the axes based on change in projection of the magnetic field on the orthogonal axes in the measurements that correlates to the object's angular displacement, and
 determine the magnetic field sensor's angular displacement and/or position, in an existing magnetic field, as a composition of measured change in projections of the magnetic field onto the orthogonal axes of the magnetic field sensor, to measure a rate of angular displacement of the object for each of the orthogonal axes. 
 
     
     
       9. The system as claimed in  claim 7  wherein, the processor, with instructions, is further configured to:
 determine the number of peaks from the scalar measurements from all of the orthogonal axes, and 
 compute a composite rate of angular displacement of the traveling object as a function of square root of sum of squares of the rate of angular displacement about one or more of the orthogonal axes. 
 
     
     
       10. The system as claimed in  claim 7  wherein, the processor, with instructions, is further configured to:
 compute a square root of sum of squares of the scalar measurements from all of the orthogonal axes to obtain a computed value, 
 count the number of peaks in the computed value, and 
 compute a composite rate of angular displacement of the traveling object about one or more of the orthogonal axes using the computed value and the counted number of peaks. 
 
     
     
       11. The system as claimed in  claim 7 , further comprising:
 a frequency-to-voltage converter communicably coupled to the processor, wherein the converter is configured to determine a value proportional to a frequency of the determined number of peaks, detected by the peak counter, in the measurements. 
 
     
     
       12. The system as claimed in  claim 7 , wherein, the processor, with instructions, is further configured to determine:
 angular displacement of the traveling object for each of the orthogonal axes; 
 rate of angular displacement of the traveling object for each of the orthogonal axes; and/or 
 change in angle and/or orientation of the object. 
 
     
     
       13. The system as claimed in  claim 7 , wherein the system further comprises:
 an inertial measurement unit including one or more of a single-axis accelerometer or a multi-axis accelerometer providing accelerometer data, wherein the processor, with instructions is further configured to,
 compute a position of the traveling object by using orientation data to compensate for gravity on the accelerometer data and double integrating the accelerometer data. 
 
 
     
     
       14. The system as claimed in  claim 7 , wherein the magnetic field sensor is a single device with three orthogonal sense axes. 
     
     
       15. The system as claimed in  claim 7 , wherein the magnetic field sensor is a sensor selected from a group consisting of, a 1-axis magnetic field sensor, a 2-axis magnetic field sensor, and a 3-axis magnetic field sensor. 
     
     
       16. The system as claimed in  claim 7 , wherein,
 the system is configured to vary the number of measurements and/or vary the time duration based on a magnetic field across a trajectory of the object. 
 
     
     
       17. A system for measuring the rate of angular displacement of an object traveling along a trajectory using magnetic field sensing, the system comprising: a magnetic field sensor in the travelling object, wherein the sensor is configured to output magnetic field sensor signals of magnetic field intensity and/or changes in the magnetic field intensity, projected onto the magnetic field sensor; a transmitter configured to transmit the signals; a receiver configured to receive the data transmitted from the transmitter; and a processor coupled with a non-transitory computer readable storage medium storing instructions that, when executed by the processor, causes the processor to: compute a composite average rate of angular displacement by, reducing noise from the data to achieve relatively higher fidelity data, segmenting the trajectory from the relatively higher fidelity data; counting a number of peaks in the relatively higher fidelity data for a time duration using a threshold parameter optimized for corresponding segmented trajectories, wherein the number of peaks is determined from determining regions where the relatively higher fidelity data have a zero slope; and compute an orientation of the traveling object by integrating the composite average rate of angular displacement. 
     
     
       18. A system as claimed in  claim 17 , further comprising:
 one or more of a single-axis accelerometer or a multi-axis accelerometer providing accelerometer data, wherein the processor is further configured to compute a position of the traveling object by using orientation data to compensate for gravity on accelerometer measurement and double integrating the accelerometer data. 
 
     
     
       19. A system as claimed in  claim 17  wherein, the system comprising:
 one or more of a single-axis gyroscope or a multi-axis gyroscope providing gyroscope data, wherein the processor is further configured to use the gyroscope data to verify fidelity of the computed orientation of the traveling object. 
 
     
     
       20. A system as claimed in  claim 17 , wherein the traveling object is one of, a linearly traveling object, an angularly displacing traveling object, and a linearly traveling angularly displacing object. 
     
     
       21. A system as claimed in  claim 17 , wherein the magnetic field sensor is embedded in the travelling object.